43 



The experimental data showing the grams of nitrogen and per 



cent of total nitrogen are found in Table VII. 



Table VII. Nitrogen distribu tion in an acid "muck" soil. 



Total N 



Ammonia N 



Humin N 



Basic N 



Basic N set free as NH 3 by 50% KOH 



Basic N not set free as NH 3 by 50% KOH 



Ammo N of bases 



Non-amino N of bases 



N in filtrate from bases 



Ammo N in filtrate from bases 



Non-amino N in filtrate from bases 



Total N regained 



0.3350 

 0.0653 

 0.0925 

 0.0454 

 0.0104 

 0.0350 

 0.0306 

 0.0148 

 0.1300 

 0.1133 

 0.0167 

 0.3332 



19.49 

 27.61 

 13.55 



3.10 

 10.45 



9.13 



4.42 

 38.81 

 33.82 



4.99 

 99.46 



5. Fargo clay loam. Duplicate portions of 250 grams were 

 hydroh zed for 48 hours. The "hitinin" precipitate required 100 cc. 

 sulfuric acid for the digestion. After digestion the material was 

 transferred to a 500 cc. flask and 21>0 cc. portions used for the dis- 

 tillation. This method was followed subsequently with th'e "humin" 

 nitrogen determination of all the mineral soils. 



The nitrate from "humin" was of a sirupy consistency in each 

 case. The first addition of 15 grams of phosphotungstic acid did 

 not entirely precipitate the bases. Five gram portions were added 

 from time to time until a total of 50 grams had been used. After 

 standing the usual length of time the precipitate of the bases was 

 filtered off, but even then the wash water caused the formation of 

 a small additional precipitate in the filtrate. After warming on the 

 steam bath this final solution was perfectly clear, and on standing 

 over night, only a trace of precipitate was formed so the precipita- 

 tion was considered complete. It appears probable that a portion 

 of this precipitate is due to the formation of inorganic phospho- 

 tungstates which consume a very large amount of the phospho- 

 tungstic acid, for if all of this precipitate had consisted o.f basic 

 nitrogen compounds the amount of nitrogen recovered should have 

 been greater than the amount which was actually found. In all 

 the subsequent work 35 grams of phosphotungstic acid was used 

 for the precipitation of the bases in the hydrolysates from mineral 

 soils. 



The phosphotungstate precipitate dissolved very slowly in the 

 sodium hydroxide as did all other phosphotungstic acid precipitates 

 of the mineral soils studied. A Kjeldahl determination of the 

 barium phosphotungstate gave 0.0026 gram nitrogen. The solution 

 containing the nitrogen of the bases was made up to 100 cc. volume. 



During the concentration of the filtrate from the bases so much 

 precipitate separated, that this was filtered off and the solution 

 made up to 300 cc. volume. The salt remaining was dissolved in 

 water and also made up to a volume of 300 cc. Aliquot portions 

 were taken from each solution and combined for the different de- 

 terminations. 



